Contact roller

ABSTRACT

A contact roller according to one embodiment includes a cylindrical rubber roll main body, two spiral groove groups provided in a surface of the rubber roll main body, spiral rubber layers which is provided in the groove groups and hardness of which is lower than the rubber roll main body, and a surface rubber layer which covers a surface of the rubber roll main body and hardness of which is lower than that of the rubber roll main body. Nip pressure of the surface rubber layer corresponding to the rubber roll main body is higher than that of the surface rubber layer corresponding to the spiral rubber layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/JP2018/020616, filed on May 29, 2018, which claims priority to andthe benefit of Japanese Patent Application No. 2017-122370, filed onJun. 22, 2017. The disclosures of the above applications areincorporated herein by reference.

FIELD

The present disclosure relates to a contact roller.

BACKGROUND

In sites of manufacturing paper- or plastic-made films, the manufacturedfilm are finally rolled around take-up rolls, and then stored in theform of rolled goods. When rolling a film around a take-up roll,wrinkles may be created on the film, and air is taken in between therolled-around film layers, thus forming air layers. In order to preventwrinkles on a rolled film, or air layers between film layers, a contactroller is used to press the film on the take-up roll. However, withmerely pressing a film on a take-up roll by a contact roller, it isstill not possible to fully prevent the creation of wrinkles and theformation of air layers.

Under these circumferences, Patent Literature 1 (JP 2014-109293 A)discloses a rubber roll (contact roller) comprising a cylindrical mainbody of the rubber roll, spiral grooves which is formed in a surface ofthe rubber roll main body and turn along reverse directions to eachother with respect to a longitudinal center of the rubber roll mainbody, and rubber layers (spiral rubber layers) filled in the grooves soas to be flush with the surface of the rubber roll main body, and whosehardness is lower than that of the rubber roll main body. The spiralrubber layers filled in the grooves have hardness lower than that of therubber roll main body, and have a higher coefficient of friction.Therefore, the grip force of the spiral rubber layers to the filmpinched between the take-up roll and the rubber roll is higher ascompared to that of the rubber roll main body. Further, the spiralrubber layers are filled respectively into the spiral grooves which turnin reverse directions to each other with respect to the longitudinalcenter of the rubber roll main body as a border. With this structure,due to the difference in nip pressure between the spiral rubber layersand the rubber roll main body, a tension is generated towards right andleft ends of the rubber roll. Thus, when the rubber roll disclosed inthe Patent Literature 1 is pressed against the take-up roll with a filmsandwiched therebetween, and the film is rolled up with the take-up rollby rotating the rubber roll, for example, in the clockwise direction andthe take-up roll in the counterclockwise direction, the creation ofwrinkles of the film and the formation of the air layers between filmlayers can be prevented by the tension thus created.

SUMMARY

Recent years, there is a demand of thinning the film and improvement inthe productivity of the film by high-speed rotation of the take-up roll.Under such circumstances, if the rubber roll disclosed in the PatentLiterature 1 is applied to produce rolled goods, the following problemmay arise. That is, if a rubber roll is pressed against a take-up rollwith a film sandwiched therebetween, the film is brought into directcontact with both the rubber roll main body and the spiral rubber layershaving a frictional force higher than that of the main body. Therefore,due to the difference in nip pressure (difference of frictional force)and a subtle level difference between these members, a tensionfluctuation is generated on the boundary between the rubber roll mainbody and the spiral rubber layers. Here, if the film is thinned and thetake-up roll is rotated at high speed, the influence of the tensionfluctuation in the boundary between the rubber roll main body and aspiral rubber layer becomes large, which may cause a scratch or crack inthe surface of the film.

An object of the embodiment is to provide a contact roller which can notonly prevent wrinkles in a film and formation of air layers of betweenfilm layers, but also prevent the occurrence of a scratch or crack inthe surface of the film even if the film is thinned and the take-up rollis rotated at high speed.

The contact roller according to an embodiment is used to press a filmagainst a take-up roll when rolling the film around the take-up roll.The contact roller comprises a cylindrical rubber roll main body, twogroove groups provided in a surface of the rubber roll main body, spiralrubber layers, and surface rubber layers. The two groove groups areprovided spirally in the surface of the rubber roll main body, so as tobe separated from each other at a longitudinal central portion thereofwith a desired interval therebetween, and are arranged to turn inreverse directions to each other on both side of the longitudinalcentral portion as a border. The spiral rubber layers are providedrespectively in the two groove groups, and they have hardness lower thanthat of the rubber roll main body. A surface rubber layer covers thesurface of the rubber roll main body including the spiral rubber layers.The surface rubber layer has hardness lower than that of the rubber rollmain body. The nip pressure of a surface of the surface rubber layer,which corresponds to the rubber roll main body, is higher than the nippressure of the surface of the surface rubber layer, which correspondsto the spiral rubber layers.

According to the embodiment, a contact roller can be provided, which cannot only prevent wrinkles to be created in a film and formation of airlayers of between film layers, but also prevent the occurrence of ascratch or crack in the surface of the film even if the film is thinnedand the take-up roll is rotated at high speed, and further which canimprove the package density of the film onto the take-up roll, thedimensional accuracy of the film along it width direction, and thequality of the film.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a perspective view showing an example of a contact rolleraccording to an embodiment.

FIG. 2 is a cross sectional view briefly showing a portion of theexample of the contact roller of the embodiment.

FIG. 3 is a development showing the example of a rubber roll main bodyand spiral rubber layers of the contact roller of the embodiment.

FIG. 4 is a flow chart illustrating an example of a manufacturingprocess of the contact roller of the embodiment.

FIG. 5 is a perspective view showing an example of a situation where thecontact roller of the embodiment is in operation.

DETAILED DESCRIPTION

Embodiments will now be described with reference to the accompanyingdrawings. Note that the drawings are schematic ones, in which scalingmay not be exact.

FIG. 1 is a perspective view showing an example of the contact rolleraccording to an embodiment.

A contact roller 1 is used to press a film against a take-up roll whilethe film is rolled around the take-up roll.

The contact roller 1 comprises a cored bar 2, a rubber roll main body 3,the two groove groups 61 and 62, spiral rubber layers 4, and a surfacerubber layer 5. The cored bar 2 comprises a rotating shaft 21 insertedto the rubber roll main body 3, and a sleeve 22 interposed between therotating shaft 21 and the rubber roll main body 3. The sleeve 22supports the rubber roll main body 3 and the rotating shaft 21 supportsthe sleeve 22 and the rubber roll main body 3, and rotates the sleeve 22and the rubber roll main body 3. The contact roller 1 may furthercomprise a underlayer (not shown) between the rubber roll main body 3and the cored bar 2. The material of the underlayer may preferably be,for example, ebonite, FRP, rubber, resin, or a combination of any ofthese.

The two groove groups 61 and 62, which respectively include grooves 6 ato 6 c and grooves 6 d to 6 f, are provided in the surface of the rubberroll main body 3. The two groove groups 61 and 62 are provided spirallyin the surface of the rubber roll main body 3, so as to be separatedfrom each other at a longitudinal central portion of the rubber rollmain body 3 with a desired interval therebetween, and are arranged toturn in reverse directions to each other on both side of thelongitudinal central portion as a border. The spiral rubber layers 4 areprovided respectively in the two groove groups 61 and 62. The spiralrubber layers 4 have hardness lower than that of the rubber roll mainbody 3. A surface rubber layer 5 is provided to cover the surface of therubber roll main body 3 including the spiral rubber layers 4. Thesurface rubber layer 5 has hardness lower than that of the rubber rollmain body 3. The nip pressure of a surface of the surface rubber layer 5corresponding to the rubber roll main body 3, that is, the surface ofthe part of the surface rubber layer 5 in contact with the rubber rollmain body 3 is higher than the nip pressure of the surface of thesurface rubber layer 5 corresponding to the spiral rubber layers 4, thatis, the surface of the part of the surface rubber layer 5 in contactwith the spiral rubber layers 4.

In this specification, the nip pressure is defined as a pressure appliedon a contact surface between the film and the contact roller while usingthe contact roller of the embodiment, which is generated when thecontact roller is pressed against the take-up roll with a filmsandwiched therebetween. This pressure is produced by the pressure onthe film by the contact roller and the repulsion force of the film tothe contact roller.

Factors of the reason why the nip pressure of the surface of the surfacerubber layer 5 in contact with the rubber roll main body 3 is higherthan the nip pressure of the surface of the surface rubber layer 5 incontact with the spiral rubber layers 4 will be described below. Thefactors of the reason are: 1) the hardness of the rubber roll main body3 is higher than the hardness of the surface rubber layer 5 and thespiral rubber layers 4; and 2) the relationship between the thickness ofthe spiral rubber layers 4 and the thickness of the surface rubber layer5.

The factors 1) and 2) will be further described below.

1) The hardness of the rubber roll main body 3 being higher than thehardness of the surface rubber layer 5 and the spiral rubber layers 4

The hardness of the rubber roll main body 3 may preferably be set tosuch a degree that when the contact roller 1 is pressed against thetake-up roll, the surface of the contact roller 1 pressed against thetake-up roll is depressed by about 0.05 mm to 0.1 mm so that a desirablearea of the surface of the contact roller 1 is brought into contact withthe film. The upper limit of such hardness is, for example, about 1/10of elastic modulus of iron and may preferably be less than 100° by JISAhardness. The lower limit of the hardness of the rubber roll main body 3may preferably be 80° by JISA hardness. When the hardness of the rubberroll main body 3 is less than a JISA hardness of 80°, there is apossibility that the efficiency of pushes air outside from between filmlayers when rolling up by the take-up roll may be lowering.

It suffices if there is a difference between the hardness of the spiralrubber layers 4 and the rubber roll main body 3, and between thehardness of the surface rubber layer 5 and the rubber roll main body 3.When the JISA hardness is applied, the difference in hardness maypreferably be, for example, 15° to 60°. If the hardness difference isless than 15°, it becomes difficult to make a sufficient difference innip pressure between the surface of the surface rubber layer 5corresponding to the rubber roll main body 3 and the surface of thesurface rubber layer 5 corresponding to the spiral rubber layers 4. Ifthe hardness difference exceeds 60°, there is a possibility that thedifference in deformation amount by an external pressure becomesexcessively large, which may cause destruction of the groove structureand shortening of the roll life.

The hardness of the spiral rubber layer 4 and that of the surface rubberlayer 5 may be the same as or different from each other. When they aredifferent, it is preferable that the hardness of the surface rubberlayer 5 be higher than that of the spiral rubber layers 4.

Preferable usable materials for the rubber roll main body 3, the spiralrubber layers 4 and the surface rubber layer 5 having such hardness are,for example, rubber or resin. Examples of the rubber may beacrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR),chlorosulfonated polyethylene rubber (CSM), ethylene propylene rubber(EPDM), butyl rubber (IIR), silicone rubber (Q), fluorocarbon rubber(FQM), urethane rubber (U), or a mixture of any of these. Examples ofthe resin may be urethane resin, epoxy resin, urea-resin, or a mixtureof any of these. It suffices if the material each of the rubber rollmain body 3, the spiral rubber layers 4 and the surface rubber layer 5is selected from materials which satisfy the conditions of the hardnessdifference discussed above. For example, the spiral rubber layer 4 andthe surface rubber layer 5 may be made from materials having the samehardness. It is preferably if the rubber roll main body 3 and the spiralrubber layers 4 are both made from chloroprene rubbers having theabove-described hardness difference, because in which case, they can beadhered well to each other.

2) Relationship between the thickness of the spiral rubber layer 4 andthe thickness of the surface rubber layer 5

The relationship will be described with reference to FIG. 2. FIG. 2 is across section briefly showing a portion of the contact roller 1 when itis cut normal to the spiral rubber layers 4.

A thickness t₂ of the spiral rubber layers 4 may preferably be 3 mm orgreater, and more preferably 4 mm or greater but 10 mm or less. If thethickness t₂ is less than 3 mm, it becomes difficult to make asufficient difference in nip pressure between the surface of the surfacerubber layer 5 corresponding to the rubber roll main body 3 and thesurface of the surface rubber layer 5 corresponding to the spiral rubberlayers 4.

A thickness t₃ of the surface rubber layer 5 may preferably be, forexample, less than 6 mm, or more preferably, the thickness t₃ is 5 mm orless. It is furthermore preferable if the thickness t₃ is 2 mm or less.When the thickness t₃ of the surface rubber layer 5 is less than 6 mm,the difference in hardness between the rubber roll main body 3 and thespiral rubber layers 4 can be expressed as the nip pressure differencein the surface of the surface rubber layer 5. As the thickness t₃ isless, the difference in hardness between the rubber roll main body 3 andthe spiral rubber layers 4 can be more prominently expressed in thesurface of the surface rubber layer 5. However, when the thickness t₃ isless than 1 mm, there is a possibility that the surface rubber layer 5may be damaged by wear or the like.

It is preferable that the thickness t₃ of the surface rubber layer 5 beless than the thickness t₂ of the spiral rubber layers 4.

Therefore, when the two factors described above are combined or selectedproperly, the nip pressure of the surface of the surface rubber layer 5corresponding to the rubber roll main body 3 can be made into a valuehigher than the nip pressure of the surface of the surface rubber layer5 in contact with the spiral rubber layer 4. As a result, the differencein nip pressure is expressed as a difference in frictional force in thesurface of the surface rubber layer as will be discussed later indetail. Thus, when the contact roller 1 of the embodiment is pressedagainst the take-up roll with a film sandwiched therebetween, and thefilm is rolled around with the take-up roll, it is possible toeffectively prevent the creation of wrinkles and formation of air layersbetween rolled film layers as will be described later.

Each member which constitutes the contact roller 1 shown in FIG. 1 willnow be described in detail using FIGS. 1 and 2, described above, andalso FIG. 3. FIG. 3 is a development showing the rubber roll main body 3and the spiral rubber layers 3 of the contact roller 1.

The cored bar 2 of the contact roller 1 shown in FIG. 1 comprises therotating shaft 21 and the sleeve 22.

It suffices if the rotating shaft 21 is a well-known shaft used for aroll employed in a line of rolling up of a film. The rotating shaft 21having such a structure is made from, for example, a metal or a carbonfiber composite material. An example of the carbon composite material isCFRP. In the case where the rotating shaft 21 is made from a carbonfiber composite material, the entire weight can be lightened whilemaintaining the strength of the contact roller 1, and it becomes simpleto handle, which is preferable.

It is preferable that the sleeve be made from, for example, a metal or acarbon fiber composite material.

Note that the cored bar 2 does not necessarily comprise the sleeve 22.Or the cored bar 2 does not necessarily comprise a rotating shaft in thecase where the contact roller 1 is distributed, in which the rubber rollmain body 3 is supported using the sleeve 22 as a cored bar, and therotating shaft of the sleeve is mounted by the user side, and to be usedin the manufacturing site of a film.

It suffices if the rubber roll main body 3 is made to have a rubberthickness t₁ shown in FIG. 2, which is greater than a depth d of thegrooves. The rubber thickness t₁ can be, for example, 5 mm to 30 mm.

The two groove groups 61 and 62 respectively including the spiralgrooves 6 a to 6 c and the grooves 6 d to 6 f are provided in thesurface of the rubber roll main body 3. The groove group 61 includingthe grooves 6 a to 6 c is formed from the longitudinal center to one endof the rubber roll main body 3, and the other groove group 62 includingthe grooves 6 d to 6 f is formed from the longitudinal center to theother end side. The groove group 61 and the groove group 62 may be intouch in the longitudinal center of the contact roller 1, or may beseparated from each other at a desired interval a therebetween (FIG. 3).The interval a may preferably be 20 mm or less. The interval a may morepreferably be 5 mm to 15 mm. When the interval a exceeds 20 mm, wrinklesor excessive air in the film contacting near the longitudinal center ofthe contact roller 1 may not be removed.

The grooves included in the groove group 61 and the grooves included inthe groove group 62 have spiral shapes which turn in reverse directionsto each other. The grooves included in the same groove group arearranged spirally and parallel to each other. A interval b between thegrooves included in the same groove group (see FIGS. 2 and 3) isdetermined so that the contact roller 1 exhibits the desired effect ofpreventing wrinkles and/or the effect of pushing out air, according tothe width w of the grooves, an outer diameter of the rubber roll mainbody 3, the hardness of the spiral rubber layer 4 and the like, whichwill be described later. The interval b may preferably be, for example,5 mm to 50 mm. The interval b may more preferably be 8 mm to 20 mm.

The width w of each groove shown in FIG. 2 is determined so that thecontact roller 1 exhibits the desired effect of preventing wrinklesand/or the effect of pushing out air, according to, for example, theouter diameter of the rubber roll main body 3 and the hardness of thespiral rubber layer 4 and the like. The width w of the grooves maypreferably be, for example, 5 mm to 30 mm. The width w may morepreferably be 8 mm to 20 mm, and even more preferably 9 mm to 20 mm.

The depth d of the grooves shown in FIG. 2 is determined according tothe thickness t₂ of the spiral rubber layers 4. The depth d is, forexample, the same as the thickness t₂ of the spiral rubber layers orless than the thickness t₂. The depth d is, for example, 3 mm orgreater.

FIG. 2 shows grooves having a rectangular sectional shape, but thesectional shape of the groove may be, for example, inverted trapezoidal.When the grooves are formed into an inverted trapezoidal shape, itbecomes easy to push air out of grooves when filling the grooves withthe spiral rubber layers 4. Thus, the spiral rubber layers 4 and therubber roll main body 3 can be adhered to each other well.

An angle θ shown in FIG. 3 made by the groove groups 61 and 62 and anauxiliary line x which indicates the longitudinal center of the rubberroll main body 3 may preferably be, for example, 10° to 120°. By settingthe angle as such, the effect of preventing wrinkles and/or the effectof pushing out air can be further enhanced.

The number of grooves included in each groove group is not limited tothe number shown in FIGS. 1 to 3, and, for example, one to twelvethreads of grooves may be provided per one groove group.

The surface of the surface rubber layer 5, which corresponds to therubber roll main body 3, may protrude from the surface of the surfacerubber layer 5, which corresponds to the spiral rubber layers 4. Orconversely, the surface of the surface rubber layer 5, which correspondsto the spiral rubber layers 4, may protrude from the surface of thesurface rubber layer 5, which corresponds to the rubber roll main body3. Or regardless of arrangement of the spiral rubber layers 4, thesurface of the surface rubber layer 5 may include spiral depressed andprojecting portions arranged to turn in reverse directions to each otherwith respect to the longitudinal central portion as the border. Theturning direction of the spiral depressed and projecting portions, thewidth, the interval therebetween, and the angle thereof may preferablybe the same as those of the spiral rubber layers 4. When there aredepressed and projecting portions in the surface of the surface rubberlayer 5, it is preferable that the depressed and projecting portions bedepressed or project by 0.02 mm to 0.05 mm from the surface of thesurface rubber layer 5.

A friction coefficient μ of the surface of the surface rubber layer 5covering the surface of the rubber roll main body 3 including the spiralrubber layers 4 may preferably be less than 0.8. When the frictioncoefficient μ is less than 0.5, the frictional resistance is reduced andtherefore the film is not scratched. Further, the wear resistance of thesurface rubber layer improves to extend the life thereof, which is morepreferable. The surface of the surface rubber layer 5 which has such acoefficient of friction can be realized by setting the surface roughnessRa thereof to less than 1.0. When the surface roughness Ra is less than0.8, the coefficient of friction becomes even lower, which is morepreferable.

The rubber roll main body 3, the spiral rubber layers 4, and the surfacerubber layer 5 may preferably be electro-conductive. Here, theconductivity means that the surface resistance value is less than1×10¹³Ω/□. When the surface resistance value is in such a range, it ispossible to prevent rolling error due to the film to roll around beingcharged. In order to make the rubber roll main body 3, the spiral rubberlayers 4, and the surface rubber layer 5 conductive, it is preferable toadd a conducting material, for example, carbon powder, to the rubber orresin material described above.

It is preferable that the contact roller be manufactured by thefollowing method shown in FIG. 4.

First, in step S1, the rubber roll main body is produced by covering thesurface of the cored bar with the material of the rubber roll main bodyvia an adhesive layer, followed by vulcanization. Next, in step S2,spiral grooves having a desired angle, width, and depth are formed inthe surface of the rubber roll main body. In step S3, the grooves arefilled with the material of the spiral rubber layers, thus forming thespiral rubber layers. In the process of S3, before the material of thespiral rubber layers is filled, an adhesive may be applied to thegrooves. In the process of S4, the rubber roll main body including thespiral rubber layers is ground so as to make, for example, the surfacesof the spiral rubber layers flush with the rubber roll main body. Instep S5, the surface of the rubber roll main body including the spiralrubber layers is covered with the material of the surface rubber layer.After that, in step S6, the surface rubber layer is vulcanized, and thenin step S7, the surface of the surface rubber layer is ground.

By the above-discussed steps, such a contact roller can be manufacturedthat can prevent the creation of winkles of film, the formation of airlayers between film layers, and the occurrence of scratches in thesurface of the film, even if the film is thinned and the take-up roll isrotated at high speed.

The contact roller described above operates as follows.

FIG. 5 is a perspective view showing an example of the contact roller ofthe embodiment as to how it is used. The contact roller 1 is placed asit is pressed against the take-up roll 8 with the film 7 sandwichedtherebetween (nipped). Examples of the film 7 are plastic films,metallic foils, paper or the like. When the contact roller 1 is rotated,for example, in the counterclockwise direction and the take-up roll 8 isrotated in the clockwise direction (as indicated by an arrow), the film7 is rolled around by the take-up roll 8 while being pressed by thecontact roller 1 against the take-up roll 8.

During this operation, a tension which stretches the film 7 in thedirections of the right and left ends thereof (indicated by a hollowarrow) is generated along the movement of the spiral rubber layers 4.The tension is generated for the following reasons.

When the contact roller 1 is pushed against the take-up roll 8 with thefilm 7 sandwiched therebetween, the nip pressure applied to the contactsurface between the surface of the surface rubber layer 5 whichcorresponds to the rubber roll main body 3 and the film 7 is higher thanthe nip pressure applied to the contact surface between the surface ofthe surface rubber layer 5 which corresponds to the spiral rubber layers4 and the film 7. The frictional force applied to the contact surface isproportional to the degree of the nip pressure. As a result, thefrictional force of the surface of the surface rubber layer 5 whichcorresponds to the rubber roll main body 3 is larger than the frictionalforce of the surface of the surface rubber layer 5 which corresponds tothe spiral rubber layers 4.

In the surface of the contact roller 1, i.e., the surface of the surfacerubber layer 5, regions where the nip pressure (frictional force)differs from one another are arranged alternately and continuously, dueto the arrangement of the spiral rubber layers 4 arranged underneath.Furthermore, the spiral rubber layers 4 are formed to be spiral turningin reverse directions to each other, with respect to the longitudinalcenter of the contact roller 1 as the border. Therefore, if the contactroller 1 is rotated, the tension which stretches the film 7 to the rightand left ends is generated.

With this tension, the creation of wrinkles in the film 7 can besuppressed. At the same time, the air sandwiched between layers of thefilm 7 is carried in the direction of the right and left ends and pushedout. Therefore, even in the state where the surface rubber layer 5 isapplied on the surface of the rubber roll main body 3 including thespiral rubber layers 4, the effect of prevention wrinkles and the effectof pushing out air can be exhibited as in the case where the rubber rollmain body 3 and the spiral rubber layers 4 are in direct contact withthe film 7.

In the contact roller 1, due to the surface rubber layer being furtherapplied onto the rubber roll main body 3 and the spiral rubber layers 4,the film 7 can be brought into contact with the surface of the smoothsurface rubber layer 5, thereby making it possible to avoid the film 7from being brought into direct contact with the surface of the rubberroll main body 3 including the spiral rubber layers 4. As a result, itis possible to prevent scratching the film 7 on the boundary of therubber roll main body 3 and the spiral rubber layers 4, which may becaused by the difference in nip pressure and the tension fluctuation bythe fine level difference on the boundary of the rubber roll main body 3and the spiral rubber layers 4 as in Patent Literature 1 discussed inthe background art. Therefore, even if the film 7 is thinned and thetake-up roll 8 is rotated at high speed, a high-quality film whichprevents the scratching can be rolled around the take-up roll.

As a further effect by covering the rubber roll main body 3 and thespiral rubber layers 4 by the surface rubber layer, it is possible toprevent degradation of the rubber roll main body 3 and the spiral rubberlayers 4. Examples of the degradation are cracking, wearing, deformationand/or adhesion of a foreign substance, or insertion of a foreignsubstance between the rubber roll main body 3 and the spiral rubberlayers 4. Further, by existence of the surface rubber layer 5, it ispossible to prevent the pattern of the rubber roll main body 3 and thespiral rubber layers 4 from being transferred onto the film 7.Furthermore, since there are no boundary lines or level differences bystructural members in the surface of the contact roller 1, the qualitycontrol including the cleaning of the contact roller 1 itself, can beconducted in a more simple way.

With these effects exhibited, according to the embodiments, a contactroller can be provided, which can not only prevent wrinkles to becreated in a film and formation of air layers of between film layers,but also prevent the occurrence of a scratch or crack in the surface ofthe film even if the film is thinned and the take-up roll is rotated athigh speed, and further which can improve the package density of thefilm onto the take-up roll, the dimensional accuracy of the film alongit width direction, and the quality of the film.

EXAMPLE

An example in which a contact roller of the embodiments was manufacturedand used will now be provided below.

A CFRP (having an outer diameter of 310 mm and a length of 8900 mm) ascored bar was covered by a special conductivity CR (having a surfaceresistance value of 10⁶ Ω/cm) as a rubber roll main body. The thicknessof the rubber roll main body was 13 mm. The hardness of the rubber rollmain body was 98 of the JISA hardness. In the surface of the rubber rollmain body, twelve threads of spiral grooves each having a width of10±0.2 mm and a depth of 5±0.2 mm were provided at intervalstherebetween of 10±0.2 mm. The angle θ of turning of the spiral of thegroove groups was 12.66°. The interval between two groove groups in thelongitudinal center of the contact roller was 10 mm.

The groove groups were filled with the special conductivity CR (having asurface resistance value of 10⁶ Ω/cm) as the spiral rubber layers. Thehardness of the spiral rubber layers was 40 to 45 of the JISA hardness.The surface of the rubber roll main body including the spiral rubberlayers was covered with the special conductivity CR (having a surfaceresistance value of 10⁶ Ω/cm) as the surface rubber layer. The thicknessof the surface rubber layer was 2±0.2 mm. The hardness of the surfacerubber layer was 40 to 45 of the JISA hardness. The surface of thesurface rubber layer was ground, and processed to KS treatment to have acoefficient of friction μ=0.4 and a surface roughness Ra=0.6. The outerdiameter of the contact roller as the final product was 340 mm.

A plastic film (made from PET, 10 μm in thickness, and 8500 mm in width)was rolled around using the contact roller manufactured as describedabove. The rolling-up speed was 400 m/min. Wrinkles, scratches, orpattern transfer were not observed in the thus film.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A contact roller for pressing a film against atake-up roll when rolling the film around with the take-up roll, thecontact roller comprising: a cylindrical rubber roll main body; twospiral groove groups provided in a surface of the rubber roll main body,so as to be separated from each other at a longitudinal center of therubber roll main body with desired interval and turn in reversedirections to each other on both sides of the longitudinal center as aborder; spiral rubber layers provided in the two groove groupsrespectively and having hardness lower than the hardness of the rubberroll main body; and a surface rubber layer provided to cover a surfaceof the rubber roll main body including the spiral rubber layers andhaving hardness lower than the hardness of the rubber roll main body,wherein nip pressure of the surface of the surface rubber layer, whichcorresponds to the rubber roll main body, is higher than nip pressure ofthe surface of the surface rubber layer, which corresponds to the spiralrubber layers.